A wireless local area network (WLAN) is generally implemented to provide local connectivity between a wired network and one or more mobile computing devices. In a typical wireless network, all of the computing devices within the network broadcast their information to one another using radio frequency (RF) communications. WLANs are based on the IEEE 802.11 standard, which designates a wireless-Ethernet specification using a variety of modulation techniques at frequencies in the 2.4 GHz and 5 GHz license-free frequency bands, although other bands might be used with the same basic framework.
The IEEE 802.11 standard (generally referred to as “Wireless Fidelity”, or Wi-Fi) enables wireless communications with throughput rates up to 54 Mbps. Wi-Fi is essentially a certification that a manufacturer's product is interoperable with the IEEE 802.11 standard. For example, equipment carrying the “Wi-Fi” logo is certified to be interoperable with other cards that operate in peer-to-peer mode, but Wi-Fi usually incorporates at least one access point, or edge device. Most access points have an integrated Ethernet controller to connect to an existing wired-Ethernet network. A Wi-Fi wireless transceiver connects users via the access point to the rest of the LAN. The majority of Wi-Fi wireless transceivers available are in Personal Computer Memory Card International Association (PCMCIA) card form, particularly for laptop, palmtop, and other portable computers. However, Wi-Fi transceivers can also be implemented through an Industry Standard Architecture (ISA) slot or Peripheral Component Interconnect (PCI) slot in a desktop computer, mini-PCI cards embedded in a laptop computer, a Universal Serial Bus (USB), or can be fully integrated within a handheld device.
Modern WLANs composed of more than one access point with overlapped cells require a frequency re-use pattern to minimize interference. However, available frequencies may be too few to allow for a sufficient amount of co-channel interference reduction. Recently, new quality-of-service (QoS) protocols allow for APs to share “time” as well as “frequency”. However, synchronization between APs is required for such time division multiplexing schemes. One prior art arrangement for providing synchronization between access points is discussed in U.S. Pat. No. 6,917,804, issued to T. Takayama et al. on Jul. 12, 2005. In this case, one access point is defined as the “master” access point and periodically transmits a “master beacon” to all remaining access points in the WLAN. Such an arrangement, however requires each access point to be equipped with additional receiving and synchronization components.
A need remains, therefore, for an arrangement that allows for synchronization of access points with little additional overhead, while maintaining the reliability of a wired connection.